Dry distilled coal has an active surface that is prone to bonding with oxygen. As such, storage as-is poses a risk of spontaneous combustion due to the heat of reaction with oxygen in the air. For this reason, there are attempts to prevent spontaneous combustion during storage by deactivating the coal through oxygen bonding on the surface of the coal ahead of time, performed by exposing the dry distilled coal to an atmosphere of processing gas that includes oxygen.